Fiberglass/gel coat pool cleaner

Jun 8, 2004
10,373
-na -NA Anywhere USA
It has been a long time which I need to know what cleaner or process you would do. I am volunteering to clean an indoor pool that is stained brown from being filled from a well. It could be iron and have suggested installing a water softner but how would you get that iron stain off without compounding, sanding, etc.
Someone suggested Easy on/Easy off. Any suggestions. Thank you and Happy New year. Now to finish a large new basement this winter with framing, installation of split heat and air units (4) and electrical done in 7 weeks. I am too old for this.
Crazy Dave
 
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Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
I would try Spray Nine first, followed by Lime Away, followed by Mary Kate On and Off.
Good luck. Let us know when you have the billard table install finished.
 
Apr 11, 2010
969
Hunter 38 Whitehall MI
I've used Serious Marine Cleaner on the top sides in the spring prior to the polish process. Cleans streaks and stains very well.

For hard water stains you can also try Lysol toilet bowel cleaner, lime away, or even TSP (tri sodium phosphate) available in paint stores. But wear gloves !
 
Sep 25, 2008
7,336
Alden 50 Sarasota, Florida
That is a common problem in pools here. I guess you could try any of the 'home remedies' suggested but there is a product sold in pool stores here specifically made for that purpose, I.e., removing iron stains. Simply dump the packet in the pool, lower the pH to 7 if it is high as directed with muriatic acid and run the filter.
I've only used it once and it was very effective. Unfortunately, it's been a couple of years and I forgot the brand name.
 
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Jun 2, 2004
3,498
Hunter 23.5 Fort Walton Yacht Club, Florida
We had some rust stains on ours and I am pretty sure the pool cleaning girl we had used muriatic acid. I suppose mostly because that is what was here and what is used in a pool all the time. I have seen purpose made rust stain cleaners for pools but it may just be muriatic acid in a prettier bottle. I can ask at the pool store when I go to get the water checked tomorrow if you have not figured it out by then.
 
Jan 19, 2010
12,553
Hobie 16 & Rhodes 22 Skeeter Charleston
Muriatic Acid is the same thing as hydrochloric acid. It will attack anything metal in the pool.... especially aluminum... so it would not be my first choice and if you go that route, I would keep it very dilute

BUT! You have a very good (and inexpensive) choice.

OXALIC acid chelates (binds to) Iron (III) which is the oxidation state of iron in rust. The chelation process makes the iron ion water soluble and as a result, the rust "dissolves" into the water...That will absolutely do the trick. I've used oxalic acid to pull rust stains out of concrete before....You can get oxalic acid in a number of products... Bar Keeper's friend is an oxalic acid product and I think the Rit dye rust remover you see at Walmart is just simply oxalic acid. But you will pay way too much for what you need to treat an entire pool. Go to a plumber's supply house and see if you can get strait up oxalic acid in bulk... (it is a white crystalline powder) also...I did a google search and found a 10lb bag for $25. That is the ticket. Drain the pool to get rid of the chlorinated water... then put the oxalic acid in the pool, fill with fresh water and let the circulation system move the water around for a few days..... drain again and refill the pool as needed. .... charge way too much for all of your efforts and laugh in your beer as you cash the check... oh wait.... I see you are volunteering.... well at least complain a lot about how hard it was to clean... :)
 
Sep 25, 2008
7,336
Alden 50 Sarasota, Florida
Muriatic acid is a dilute form of HCl intended to allow the iron to solubalize by lowering the pH. The iron will adhere to the pool surface if the pH is too high. The active component of the 'stuff' sold in pool stores is oxalic acid. Used as directed, neither will harm anything.
 
Jan 19, 2010
12,553
Hobie 16 & Rhodes 22 Skeeter Charleston
Don't want to quibble but don't handle muriatic acid without taking proper precautions...
From JamesTown Distributors (see description)
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yes it is described as a pool cleaner... but it will attack metals so ... go with oxalic acid. Oxalic works better and there is less chance of miss using it. Also it costs a lot less....
 

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Jun 2, 2004
3,498
Hunter 23.5 Fort Walton Yacht Club, Florida
Answer from our pool guys.
First add a "metal isolator" she showed me one on the shelf I forgot the name on it. Without that as soon as you add clhorine the stain will come back.
Second do an "acid wash" using muriatic acid often that takes care of the staining and is cheap.
Third try one of the metal stain cleaning product she showed me one it was about the size of a thing of baby powde and was $25 she said it would take two or three to do a whole pool and you can cut down on how much you need by doing the acid wash.

We want to see you sporting your "Pool Cleaning Merit Badge" when you get it done.

Forgot to add she asked if the pool was empty. Down here most places we can't empty them all the way because the ground water level is so high it will pop the pool up out of the ground. If empty she suggested removing the screws in the drain cover and the drain cover if metal then a garden sprayer filled half with water the other half muriatic acid and spraying it down keeping it away from the ladder and any other metal parts. If you were closer I'd come help you, good luck.
i
 
Sep 25, 2008
7,336
Alden 50 Sarasota, Florida
That's the common method to which I referred.
"Second do an "acid wash" using muriatic acid often that takes care of the staining and is cheap.
Third try one of the metal stain cleaning product she showed me one it was about the size of a thing of baby powde and was $25 she said it would take two or three to do a whole pool and you can cut down on how much you need by doing the acid was
h"


However, in most cases, it is impracticable to empty a pool but my experience in removing rust stains over the years is that isn't necessary.
 

capta

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Jun 4, 2009
4,905
Pearson 530 Admiralty Bay, Bequia SVG
Ever wonder how the cruise ships keep their hulls looking so clean and white? I can assure you bit isn't paint, muriatic acid, oxalic acid or anything expensive like Mary Kate On and Off.
Try phosphoric acid. Often sold under the trade name of Ospho, you can roll it on, spray it on or brush it on. It's pretty safe to use especially compared to muriatic acid and it's only job around any boat I've been on is to remove rust stains. It may take several coats, but it just washes off with water when you are done. Also available in 55 gallon drums for those really big jobs.
 
Jul 8, 2012
137
Catalina 36 MKII North East
My pool is fiberglass and I've cleaned it several times with oxalic acid - works great, neighborhood kids would gather to watch. With the pool full and properly prepped, when you dump the acid powder in it is like a clean cloud spreading underwater - in ten minutes the surfaces are perfectly clean.
Search for "Stain Out" on You Tube - annoying music but you'll see how quick it works.
Key steps are lowering the chlorine as per instructions, use Metal X (the X stands for expen$ive) or other metal remover (forget if it is before or after, read instructions), use the acid then change the filter material the next day. Then start the chlorine again. If you skip[ the metalX the stain will be back in days.
Last time I used oxalic acid bought on the internet, it was cheaper and worked fine. For spot stain removal a sock full of vitamin C tablets will work too.